A DC power supply device used for a plasma generator is required to suppress excess current at the time of arc occurrence, and to extinguish the arc at a high speed. A voltage type direct power source has problems as the following; a large capacitor which is connected to output may cause a flow of excessive discharge current at the time of arc occurrence, and the output power is further increased in order to compensate for reduction of output voltage upon arc occurrence, thereby elongating the arcing time and resulting in increase of impact on the load.
When the plasma generator is assumed as the load, the direct power supply has to repeat a startup operation and a stop operation every generation of arc. Since it is difficult to perform the startup operation and the stop operation at high speed, this may lead to unstable operations. In order to address those problems above, there is suggested a DC power supply device provided with a chopper circuit, an inverter, and a voltage conversion circuit, being stable in the startup operation and being able to start and stop the load at high speed, the DC power supply device executing any one of following operations upon suspending; a stop operation in which the inverter is activated along with stopping a main switch of the chopper, a stop operation in which all the transistors of the inverter are turned on in the state where the main switch of the chopper is activated, and a stop operation in which all the transistors in the inverter are turned on along with stopping the main switch of the chopper, and the DC power supply device executing following operations at the startup timing; the inverter is activated and a pulse width of a DC voltage pulse outputted from the chopper circuit is gradually increased, thereby suppressing a large current directed to the inverter (Patent Document 1).
There is suggested an arc suppressing unit for sputtering power supply, being provided with a short-circuit switch circuit for forcing arc energy to bypass between a DC power supply device and a load, the short-circuit switch circuit is activated periodically at regular time intervals to generate inverse pulses to suppress arc discharge, and when the arc discharge occurs, the inverse pulse is forced to be generated to reduce arc energy. Then, after extinguishing arc discharge, the arc suppressing unit resumes the plasma state (Non Patent Document 1).
On the other hand, in an alternating current power supply device for supplying high-frequency power to the load, when arc discharge occurs in the plasma generator assumed as the load, there may occur a wire broken or a short in the circuit, and in addition, electrodes and substrates may be damaged. It is known that in order to suppress such occurrence of arc discharge, after detecting the arc discharge, supplying of the high-frequency power is limited or stopped for a predetermined period of time, and thereafter, the high-frequency power is resumed.
Upon suspending the supply of the high-frequency power for the predetermined period of time after detecting the arc discharge, there is a problem that if the high-frequency power supply is stopped for a time longer than necessary, maintaining of glow discharge may become difficult.
In order to address such problem as described above, there is suggested a power source for the plasma generator which supplies a pulse-like high-frequency wave after detecting the arc discharge, and controls a pulse width of the pulse-like high-frequency wave according to the magnitude of the arc discharge, thereby suppressing the arc discharge promptly after the occurrence of arc discharge and enabling activation of the plasma generator immediately after extinguishing the arc discharge (Patent Document 2).